ErythropoieSIS stimulating agent (ESA) use is increased following missed dialysis sessions

Missed dialysis sessions can have a cascading effect on patient clinical outcomes. In addition to missing the dialysis itself, patients fail to receive medications—such as ESAs—that are dosed at each session. This analysis assessed ESA dose changes following missed session episodes in order to evaluate “catch-up dosing.”In a retrospective analysis, we assessed missed session and epoetin alfa (EPO) utilization data in 2010 from adult (≥ 18 yrs old), hemodialysis (HD) patients. Consecutive misses were considered part of a missed session “episode.” All misses were included (even if patient was hospitalized). Differences in EPO utilization in the periods 14 days, 30 days and 31-60 days before and after missed session episodes were calculated and stratified by length of episode, and whether additional sessions were missed in the before/after periods. Total monthly EPO dose was also calculated and stratified by number of missed sessions.Patients used significantly more EPO after a missed session episode, and differences in per session EPO dose were generally greater the longer the episode. For missed session episodes with no additional misses in the 30 day before/after period, increases of 18% to 30% per session were seen, depending on episode length. For longer episodes, usually due to hospitalization, differences were sustained over 60 days. Analyses which included additional missed sessions in the before/after period showed similar patterns. Beyond these per-session associations, the total amount of EPO used in a month increased with number of missed sessions (through up to 5 missed sessions), even though these patients (by definition) were not receiving as many administrations of EPO.Missed session episodes result in significant increases in ESA utilization in the post-miss period, and also in total monthly ESA use. Such increases should be considered in any assessment of impact of missed sessions: both clinical and economic

Understanding radionuclide migration from the D1225 Shaft, Dounreay, Caithness, UK

A 65 m vertical shaft was sunk at Dounreay in the 1950s to build a tunnel for the offshore discharge of radioactive effluent from the various nuclear facilities then under construction. In 1959, the Shaft was licensed as a disposal facility for radioactive wastes and was routinely used for the disposal of ILW until 1970. Despite the operation of a hydraulic containment scheme, some radioactivity is known to have leaked into the surrounding rocks. Detailed logging, together with mineralogical and radiochemical analysis of drillcore has revealed four distinct bedding-parallel zones of contamination. The data show that Sr-90 dominates the bulk beta/gamma contamination signal, whereas Cs-137 and Pu-248/249 are found only to be weakly mobile, leading to very low activities and distinct clustering around the Shaft. The data also suggest that all uranium seen in the geosphere is natural in origin. At the smaller scale, contamination adjacent to fracture surfaces is present within a zone of enhanced porosity created by the dissolution of carbonate cements from the Caithness flagstones during long-term rockwater interactions. Quantitative modelling of radionuclide migration, using the multiphysics computer code QPAC shows the importance of different sorption mechanisms and different mineralogical substrates in the Caithnesss flagstones in controlling radionuclide migration

The Coordination Chemistry of the N-Donor-Substituted Phosphazanes.

Phosph(III)azanes, featuring the heterocyclobutane P2 N2 ring, have now been established as building blocks in main-group coordination and supramolecular compounds. Previous studies have largely involved their use as neutral P-donor ligands or as anionic N-donor ligands, derived from deprotonation of amido-phosphazanes [RNHP(μ-NR)]2 . The use of neutral amido-phosphazanes themselves as chelating, H-bond donors in anion receptors has also been an area of recent interest because of the ease by which the proton acidity and anion binding constants can be modulated, by the incorporation of electron-withdrawing exo- and endo-cyclic groups (R) and by the coordination of transition metals to the ring P atoms. We observed recently that the effect of P,N-chelation of metal atoms to the P atoms of cis-[(2-py)NHP(μ-Nt Bu)]2 (2-py=2-pyridyl) not only pre-organises the N-H functionality for optimum H-bonding to anions but also results in a large increase in anion binding constants, well above those for traditional organic receptors like squaramides and ureas. Here, we report a broader investigation of ligand chemistry of [(2-py)NHP(μ-t NBu)]2 (and of the new quinolyl derivative [(8-Qu)NHP(μ-Nt Bu)]2 (8-Qu=8-quinolyl). The additional N-donor functionality of the heterocyclic substituents and its position has a marked effect on the anion and metal coordination chemistry of both species, leading to novel structural behaviour and reactivity compared to unfunctionalized counterparts.Cambridge Trus

Characterising a rock fracture rough surface using spatial continuity and kriging: a new approach to meshing coupled thermo–hydraulic–mechanical–chemical (THMC) models

Fluid flow through low permeability rocks is mainly accomplished through fractures. In order to model fluid flow, coupled thermo–hydraulic–mechanical–chemical (THMC) numerical models are used, which rely on fracture surface representations to construct a distribution model of the empty space (aperture) between the two fracture faces.The traditionally used statistical representations of fracture surfaces often overlook spatial continuity (SC), i.e. how well correlated points are in direction and distance. Examples are the fractures' aperture distribution random sampling to the joint roughness coefficient. This may result in a poor representation of the aperture distribution and thus a poor model.The first aim of this study is to investigate the possibility of characterising a fracture surface roughness using its SC parameters, an upscaled fracture surface and ordinary kriging (OK) interpolation algorithm. This method provides better control over the aperture model creation, which will have implications for its complexity and computation times. The second aim is to utilise the SC information and the distribution of a fracture in order to extrapolate (i.e. blind predict) the distribution of the fracture where no observations exist. A statistical analysis was performed in a greywacke in order to acquire the parameters necessary to describe the SC of the fracture surface topography. The surface was then interpolated using the OK algorithm. These parameters and the surface distribution will be used to inform the OK algorithm to extrapolate the fracture to where no data has yet been acquired. A reasonable match between the kriged and original surfaces has been achieved and the fit quantified by analysing the error between the two and by R2, which offer positive measurements of methodological quality. The aperture can easily be calculated from the difference between both complementary surfaces. The aperture between the two original fracture surfaces versus the two kriged fracture surfaces was also quantified and compared, yielding good results. This method may provide a new alternative to current storing and computing solutions for fracture representation, especially in aperture distribution calculation for coupled THMC numerical models and simulations. To verify advances in accuracy and computing times for this method, results between models derived from the original versus kriging aperture data will have to be compared. Another potential applicability of the SC information is to know a priori from any modelling which directions are those of Darcy's flow and which are the directions of the highest and lowest dilation rates with shearing, which will have to be confirmed with future planned modelling work